This invention relates to reusable seals that are virtually perfectly leakproof at very high to very low pressures, very low (cryogenic) to very high (500.degree. C.) temperatures, and in extremely hostile environments such as space or harsh, corrosive chemicals such as acids and other chemically reactive substances.
Conventional contact seal materials are generally of two different classes: metallic and non-metallic. The non-metallic seals are capable of excellent sealing at low cost over limited pressures and temperatures, and for a limited lifetime. However, they must be compatible with the fluid to be sealed and the environment the seal is in. The pressure, temperature and fluid compatibility issues are the greatest obstacles against using these seal materials.
Metallic seals are used to overcome the shortcomings of nonmetallic seals. However, conventional metallic seals, while allowing wider temperature and pressure capability than non-metallic seals, require a very smooth seal face against which to seal, and are susceptible to degradation caused by chemical incompatibility with the sealed fluid. Moveover, the permanent set induced in the metallic seal when it is deformed to make the seal makes this type of seal worthless for reuse.
Thus, there has long been a need in industry for a seal that remains effective over long periods of time regardless of temperature, pressure or the chemical environment, and which is economical for those reasons. This long sought seal would also have reduced need for extremely smooth machining of the seal faces and the close tolerances that have been necessary for good sealing surfaces for conventional seal materials, and would be capable of reused many times over and over again without any degradation in sealing effectiveness.